It’s always a sure sign that something has gone horribly wrong when Tory politicians can only be persuaded with extreme reluctance to support anti-terror measures pursued by the Labour government. But this is exactly what happened on Thursday, when Conservative MPs joined with the government’s own MPs to extend until March 2009 the legislation authorizing the government to hold alleged terror suspects under control orders.

The vote to extend the control orders — which are currently used against 15 alleged terror suspects — passed by 267 votes to 60, but Tory MPs were clearly not bowled over by a hyperbolic statement made by Security Minister Tony McNulty, who, as though infected by the ghosts of previous Labour hard men John Reid and David Blunkett, claimed, “The threat (of terrorism) is clearly real, serious and represents a threat unparalleled in our country’s history.”

Speaking on behalf of his fellow MPs, the Tories’ shadow attorney general Dominic Grieve declared, “On balance, and with a considerable degree of reluctance, our view is we should allow renewal to take place this year.” Other notes of caution were sounded by Labour MPs. Alex Carlile, the government’s terror laws ombudsman, said that no control order should be extended beyond two years “save in genuinely exceptional circumstances,” and Andrew Dismore, the chairman of the joint Human Rights Committee, warned that the orders could create “Guantánamo-style martyrs” unless a maximum time limit was imposed. “Perhaps it is the gilded cage of Acacia Avenue rather than the harshness of a Cuban camp,” he said, “but we have still seen indefinite restrictions on their freedom.”

A very specific kind of personal prison, control orders were introduced in March 2005 after the government’s previous method of dealing with alleged terror suspects — holding them in high-security prisons, including Belmarsh, without charge or trial — was ruled illegal by the House of Lords. Generally involving curfews, electronic tagging, the requirement to report regularly to police, and restrictions on associating with others and using telephones and computers, they constitute a kind of house arrest, and have been criticized for contravening the European Convention on Human Rights. In April 2006 the high court ruled that placing a man known only as “S” under a control order without a fair hearing infringed Article 6 of the Convention, and in June 2006 a judge quashed the control orders against six other men, ruling that they were “incompatible” with Article 5 of the Convention, which prevents indefinite detention without trial.

The reasons for the government’s insistence on using control orders were explained to the BBC by Labour MP John Denham in May last year. Denham said, “They were brought in because the courts prevented the government from jailing people who were believed to be terrorists, [and who] sometimes had a terrorist record overseas; we were stopped from jailing them because we didn’t have the evidence to convict them here.”

Critics, however, point out that holding men without charge or trial — with echoes of the US prison at Guantánamo Bay — is monstrously unjust, and that the control orders could be done away with if the government was prepared to join most other western countries in establishing ways of incorporating evidence collected by the security services in trials. At present, the government refuses to do so, leading to valid complaints that the quality of the evidence cannot be tested.

Ironically, the day after the legislation was extended for a year, the supposedly significant and sensitive intelligence used to justify imposing one of these control orders was revealed as a sham when a high court judge dismissed the control order against 25-year old British national Cerie Bullivant, ruling that there was no “reasonable suspicion” that he intended to take part in terrorism abroad. According to a report in the Guardian, MI5 had alleged that the “restriction of movement measures were necessary” because Bullivant “could be planning to travel to Iraq or Afghanistan to join up with terrorists.”

First subjected to a control order in June 2006, which was renewed last year, Mr. Bullivant became something of a terror suspect celebrity last May when he, along with two brothers, Lamine and Ibrahim Adam, disappeared after breaking the conditions of their control orders. The Adam brothers, whose other brother, Anthony Garcia, was sentenced to life in prison in April 2007 for his part in a fertilizer bomb plot, failed to report to a “monitoring company,” and Mr. Bullivant failed to turn up at a police station, which he was required to do on a daily basis. In all the hysterical reporting that followed, there was little, if any mention of the reason that Mr. Bullivant was regarded as so significantly dangerous that the government was prepared to imprison him without charge or trial, using a form of house arrest.

Yesterday, as Mr. Justice Collins quashed the control order, the government’s overreaction to the supposed “threat” posed by Mr. Bullivant was made clear. He had been subjected to a control order after he was stopped at Heathrow as he was about to board a flight to Syria with Ibrahim Adam. Mr. Bullivant said that he intended to study Arabic in Syria, but the security services decided that he and Adam intended “to carry out extremist Islamic activity,” and that they were possibly intending to travel on to Iraq or Afghanistan to fight against western forces, or to conduct a “martyrdom operation.”

Quashing the control order, Mr. Justice Collins said that it might have been “reasonable to assume that individuals with whom Bullivant associated might have been involved in terrorism, but that did not make it reasonable to suspect he had the same inclinations.” He added, “The dangers of guilt by association are obvious.”

Outside the court, Bullivant celebrated his freedom, but asked reporters to consider the other men who were still held under control orders. “Although I am very happy that this order has now been lifted,” he said, “this draconian legislation is still continuing to ruin the lives of others and their families.”